Organic light-emitting elements are elements having an anode, a cathode, and an organic compound layer between the two electrodes. In an organic light-emitting element, holes and electrons injected from the two electrodes recombine in the organic compound layer as an emitting layer and form excitons. The element emits light when the excitons return to the ground state. The recent significant advances in organic light-emitting elements have enabled us to make them into thin and lightweight light-emitting devices with low driving voltages, a wide variety of emission wavelengths, and quick response.
It is important for lower-voltage organic light-emitting elements that the elements are improved in terms of electron injection. Examples of ways to improve electron injection include those described in PTL 1 and 2, in which metal is used.
Compounds such as 1-A, 1-B, and 1-C, for which synthetic processes described in NPL 1, 2, and 3 are known, are made from instable materials and are easily oxidized in the air.

The organic light-emitting elements described in PTL 1 and 2 have an electron injection layer made from a metal-containing compound. This is advantageous in respect of electron injection, but on the other hand affects the life of the elements because such a compound is highly reactive with water.
The compounds described in NPL 1 to 3, which are susceptible to oxidation in the air, are difficult to handle in the air.